Veneer is produced by peeling a thin strip of material off the periphery of a log. This is an old well known practice and has been developed over the years. Currently it is standard practice to determine the maximum cylinder obtainable from the log so that during the peeling process the maximum amount of veneer will be realized.
The logs, of course, are not perfect. That is, they may be out of round, they are generally tapered from end to end and may have bends or bows along their length. In addition to these variations, logs may have other imperfections such as burls, knots, and the like.
The log is, therefore, scanned or measured by known methods to determine its optimum or maximum cylinder that is contained within the boundaries of the log. The axis of the determined cylinder is aligned with the rotational axis of the veneer lathe so that during the peeling process the maximum amount of veneer may be obtained from each log.
Prior devices supported the log to be scanned on rotatable spindles. The spindles would rotate the log and as the log was rotated, the log was scanned to obtain measurements along its length to determine the largest or optimum cylinder available in the log. The scan data also would determine the position of the axis of the optimum cylinder relative to the rotatable scanning spindles. In addition to the requirement of rotating, the scanning spindles were required to be movable along two axes normal to their rotational axis to facilitate positioning the axis of the optimum cylinder at a known position. A charging device was provided to grip the ends of the log at a position strategic to the determined axis of the optimum cylinder and transfer the log to the veneer lathe spindles to align the axis of the optimum cylinder with the rotational axis of the lathe spindle.
This type of scanning operation required complex and expensive equipment to support, rotate and position the log. The log had to be initially mounted in the scanning spindles to obtain measurements in addition to the ultimate mounting of the log in the lathe spindles. After the log was scanned, the scan data processed and the spindles repositioned to place the axis of the optimum cylinder at the desired position, a transfer device would be moved in to transfer the log from the scanning spindles to the lathe spindles. One of the problems with this arrangement was that as the log charging device or transfer device was moved in to pick up the log from the scanning spindles, there was a possibility of the charging device interfering with the scanning spindles due to the location of the axis of the optimum cylinder. Thus further rotative repositioning of the log may be required. A further potential problem is that the end of the log impaled by the scanning spindles must also be impaled by the peeling spindles and adjacent or overlapping of the spindle positions may prevent secure gripping by the peeling spindles and cause the peeling spindles to spin out of its grip on the log end.